Stem Cells and Cancer?
Stem cells and cancer? Every few months this topic rears it’s ugly head in the media. Regrettably, the media commentators used for this issue usually have no special knowledge or expertise in stem cell biology. Since embryonic stem cells (ESCs) can form tumors and reprogrammed skin cells turned into stem cells (IPSCs) are genetically unstable, the commentator usually confuses these issues with adult stem cells (ASCs). These stem cell types are as different as apples and oranges. In particular, the type of stem cells we use (ASCs) are designed to repair tissue in the body, which is their natural function. To the contrary, ESCs are designed to make a person, so it’s not surprising they can form tumors with many different tissue types (Teratomas). In addition, artificially inserting new genes into normal skin cells to create a pharmaceutical product (an artificial stem cell or IPSC) is a really bad idea.
The kind of ASCs which we often use to treat orthopedic injuries are called mesenchymal stem cells (MSCs) and this type has an extra safety feature-they are contact inhibited. This means that once they cover an area and the individual cells touch each other, they automatically stop growing. Pundits argue that the culturing of MSCs can cause cancer! However, again, this is yet another confused issue with a kernel of truth, but not much more. If you grow MSCs for a more than two weeks in culture, they will simply stop growing on their own. For example, in the average middle aged person, somewhere around culture day 15-21 they will simply “peter out”. This is because MSCs quickly go into “replicative senescence” after a certain number of cell divisions. After this point, if you then add “tumor conditioning media” (a chemical “witches brew” of chemicals to force normal cells to grow tumors) and keep pushing the cells well past the point where most naturally die off and a only a few abnormal cells are left, over several months you will coax abnormal cells to grow. If you then take these cells and implant them in rats bred not to have an immune system (the body system which would naturally destroy these abnormal cells), you can create a tumor. Obviously no sane person culturing MSCs would ever push them to this point nor add chemicals that grow cancer cells and then reimplant these cells into patients without an immune system, but this phenomenon is often quoted as proof that ASCs cause cancer. This is like saying that if you drive your family car at 200 mph you could die or if you jump from the tenth story of a building it can be fatal. Our process of culturing cells (Regenexx-C) only grows stem cells for on average 11-17 days and also adds the extra safety step of determining karyotype by an outside lab before we will re-inject the cells. This extra safety protocol looks for cells that are abnormal. In addition, our entire procedure uses the patient’s own growth factors from blood platelets (platelet lysate) to grow the cells rather than adding in foreign substances like fetal calf blood and recombinant growth stimulants. In fact this platelet lysate culture technique has been studied by others and found not to produce any cells capable of creating tumors. In addition, we have studied our specific technique extensively across two published studies where hundreds of research grade MRIs of the areas stem cells were placed demonstrated no safety issues (Centeno et al stem cell safety study 1 and safety study 2). In fact, the safety profile of Regenexx-C was much better than the traditional joint surgeries it helped many patients avoid. The upshot? Small kernels of truth are often blown into nonsensical arguments by those who haven’t done their homework-this is true in politics and also true in stem cells!